feat(module:collapse): add extra field

[wzhudev]

close #1911

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

Ref ant design: ant-design/ant-design#14820.

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[codecov]

Codecov Report

Merging #2923 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2923      +/-   ##
==========================================
+ Coverage   97.36%   97.36%   +<.01%     
==========================================
  Files         524      524              
  Lines       11041    11042       +1     
  Branches      782      782              
==========================================
+ Hits        10750    10751       +1     
  Misses        190      190              
  Partials      101      101

Impacted Files	Coverage Δ
components/collapse/nz-collapse-panel.component.ts	100% <100%> (ø)	⬆️

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[vthinkxie]

LGTM